A conventional induction heating device will be described with reference to the drawing.
FIG. 8 shows a circuit configuration of the conventional induction heating device. In circuits shown in FIG. 8, a rectifying circuit 22 rectifies an AC power supply 21, and a smoothing circuit 23 smooths the rectified output to obtain a DC power supply. An inverter 31a is composed of a heating coil 24a, a resonance capacitor 25a, and a switching element 26a. An inverter 31b is composed of a heating coil 24b, a resonance capacitor 25b, and a switching element 26b. An oscillating circuit 27a drives the switching element 26a included in the inverter 31a. An oscillating circuit 27b drives the switching element 26b included in the inverter 31b. An input current detecting circuit 28 detects a value of an input current, and a power supply voltage detecting circuit 29 detects a voltage of the AC power supply. A microcomputer 30 controls oscillations of the inverters 31a and 31b, based on the values detected by the input current detecting circuit 28 and the power supply voltage detecting circuit 29.
In the above configuration, the microcomputer 30 controls the oscillating circuits 27a and 27b so that the oscillating circuits 27a and 27b are alternately driven. Further, the microcomputer 30 calculates a power value based on a current value detected by the input current detecting circuit 28 and a voltage value detected by the power supply voltage detecting circuit 29 while controlling the oscillating circuit 27a, and uses the calculated power value in correcting a power of the inverter 31a or the like. Similarly, the microcomputer 30 calculates a power value based on the current value input by the input current detecting circuit 28 and the voltage value input by the power supply voltage detecting circuit 29 while controlling the oscillating circuit 27b, and uses the calculated power value in correcting the power of the inverter 31b or the like (refer to patent document 1, for example).    Patent Document 1: JP 2001-196156 A